Stabilization of superconductive La–Y alloy superhydride with Tc above 90 K at megabar pressure

Compressed superhydrides have been one of the most prominent high-temperature superconductors (e.g., CaH6, YH6/9, and LaH10). In addition to the quest for improving superconductivity, another pressing challenge in this field is to lower the stabilization pressures of these appealing materials, since their experimental characterizations are still extremely arduous at extreme pressures above 170 GPa. In this work, by virtue of the configuration entropy enhancing the stability, we provide an archetypal showcase of substitutional La–Y alloy tetrahydride (La,Y)H4 with high superconducting temperature above 90 K, which can be synthesized with a much-reduced pressure (∼110 GPa) compared to that in unalloyed binary YH4. Furthermore, (La,Y)H4 is recoverable down to ∼80 GPa that is superior to that of YH4. These findings not only demonstrate that alloy hydrides are ideal promising superconductors with outstanding properties, but more importantly, also provide an effective strategy towards achieving high-temperature superconductivity at even lower pressure, raising great prospects for hydrides.